Proviron® (mesterolone)

Proviron® is the Schering brand name for the oral androgen mesterolone (1 methyl-dihydrotestosterone). Just as with DHT, the activity of this steroid is that of a strong androgen which does not aromatize into estrogen. In clinical situations Proviron® is generally used to treat various types of sexual dysfunction, which often result from a low endogenous testosterone level. It can usually reverse problems of sexual disinterest and impotency, and is sometimes used to increase the sperm count. The drug does not stimulate the body to produce testosterone, but is simply an oral androgen substitute that is used to compensate for a lack of the natural male androgen.

Although this steroid is strongly androgenic, the anabolic effect of it is considered too weak for muscle building purposes. This is due to the fact that Proviron® is rapidly reduced to inactive metabolites in muscle tissue, a trait also characteristic of dihydrotestosterone, The belief that the weak anabolic nature of this compound indicated a tendency to block the androgen receptor in muscle tissue, thereby reducing the gains of other more potent muscle building steroids, should likewise not be taken seriously. In fact due to its extremely high affinity for plasma binding proteins such as SHBG, Proviron® may actually work to potentate the activity of other steroids by displacing a higher percentage into a free, unbound state. Among athletes Proviron® is primarily used as an antiestrogen. It is believed to act as an antiaromatase in the body, preventing or slowing the conversion of steroids into estrogen. The result is somewhat comparable to Arimidex® (though less profound), the drug acting to prevent the buildup of estrogen in the body. This is in contrast to Nolvadex®, which only blocks the ability of estrogen to bind and activate receptors in certain tissues. The anti-aromatization effect is preferred, as it is a more direct and efficient means of dealing with the problem of estrogenic side effects. A related disadvantage to Nolvadex® is that if discontinued too early, a rebound effect may occur as high serum estrogen levels are again free to take action. This of course could mean a rapid onset of side effects such as gynecomastia and water retention. Most athletes actually prefer to use both Proviron® and Nolvadex®, especially during strongly estrogenic cycles. With each item attacking estrogen at a different angle, side effects are often greatly minimized.

The anti-estrogenic properties of Proviron® are not unique to this compound. A number of steroids have in fact demonstrated similar activity. Dihydrotestosterone and Masteron (2methyl-dihydrotestosterone) for example have been successfully used as therapies for gynecomastia and breast cancer due to their strong anti-estrogenic effect. It has been suggested that nandrolone may even lower aromatase activity in peripheral tissues where it is more resistant to estrogen conversion (the most active site of nandrolone aromatization seems to be the liver). The antiestrogenic effect of all of these compounds is presumably caused by their ability to compete with other substrates for binding to the aromatase enzyme. With the aromatase enzyme bound to the steroid, yet being unable to alter it, and inhibiting effect is achieved as it is temporarily blocked from interacting with other hormones.

This drug is also favored by many during contest preparations, when a lower estrogen/high androgen level is particularly sought after. This is especially beneficial when anabolics like Winstrol®, oxandrolone and Primobolan® are being used alone, as the androgenic content of these drugs is relatively low. Proviron® can supplement a wellneeded androgen, and bring about an increase in the hardness and density of the muscles. Women in particular find a single 25mg tablet will efficiently shift the androgen/estrogen ratio, and can have a great impact on the physique. Since this is such a strong androgen however, extreme caution should be taken with administration. Higher dosages clearly have the potential to cause virilization symptoms quite readily. For this reason females will rarely take more than one tablet per day, and limit the length of intake to no longer than four or five weeks. One tablet used in conjunction with 10 or 20mg of Nolvadex® can be even more efficient for muscle hardening, creating an environment where the body is much more inclined to burn off extra body fat (especially in female trouble areas like the hips and thighs).

The typical dosage for men is one to four 25 mg per tablets per day. This is a sufficient amount to prevent gynecomastia, the drug often used throughout the duration of a strong cycle. As mentioned earlier, it is often combined with Nolvadex® (tamoxifen citrate) or Clomid® (clomiphene citrate) when heavily estrogenic steroids are being taken (Dianabol, testosterone etc.). Administering 50mg of Proviron® and 20mg Nolvadex® daily has proven extremely effective in such instances, and it is quite uncommon for higher dosages to be required. And just as we discussed for women, the androgenic nature of this compound is greatly welcome during contest preparation. Here again Proviron® should noticeably benefit the hardness and density of the muscle, while at the same time increasing the tendency to burn off a greater amount of body fat. Proviron® is usually well tolerated and side effects (men) are rare with dosages under 100 mg per day. Above this, one may develop an excessively high androgen level and encounter some problems. Typical androgenic side effects include oily skin, acne, body/facial hair growth and exacerbation of a male pattern baldness condition, and may occur even with the use of a moderate dosage. With the strong effect DHT has on the reproductive system, androgenic actions may also include an extreme heightening of male libido. And as discussed earlier, Women should be careful around Proviron®. It is an androgen, and as such has the potential to produce virilization symptoms quite readily. This includes, of course, a deepening of the voice, menstrual irregularities, changes in skin texture and clitoral enlargement.

Proviron® is also not a c17 alpha alkylated compound, an alteration commonly used with oral anabolic/androgenic steroids. Not using this structure in the case of Proviron® removes the notable risk of liver toxicity we normally associate with oral dosing. We therefore consider this a "safe" oral, the user having no need to worry about serious complications with use. This steroid in fact utilizes the same 1-methylation we see present on Primobolan® (methenolone), another well tolerated orally active compound. Alkylation at the one position also slows metabolism of the steroid during the first pass, although much less profoundly than 17 alpha alkylation. Likewise Proviron® and Primobolan® are resistant enough to breakdown to allow therapeutically beneficial blood levels to be achieved, although the overall bioavailability of these compounds is still much lower than methylated oral steroids.

The popularity of Proviron® amongst bodybuilders has been increasing in recent years. Many experienced bodybuilders have in fact come to swear by it, incorporating it effectively in most markedly estrogenic cycles. Due to high demand Proviron® is now very easy to obtain on the black market. Most versions will be manufactured by Schering, and should cost about $1-$2 per 25 mg tab. In many instances this item is obtained via mail order, and here can sell for less than .50 per tab. This drug is packaged in both push-through strips and small glass vials, so do not let this alarm you. There is currently no need to worry about authenticity with this drug, as no counterfeits are known to exist. If money and availability does not prevent it, Arimidex® is actually a much better choice than Proviron® though. This drug was designed specifically as an antiaromatase, and works much more effectively than anything else we have available. Since this item is extremely expensive however, Nolvadex® and Proviron® will no doubt remain to be the "standard" antiestrogen regimen among athletes.